Duplicate emails can sent out when a workflow is set to start when an item is modified and you are not checking to see if that same email has already been sent out. To prevent duplicate emails from being sent out each time the item is modified, either:
A. Only start the workflow when items are created. For example if you have confirmation email that just needs to be sent out when a new item is created, create a workflow that only starts when an item is created. If you try to combine the confirmation email into a workflow that also starts when items are modified, the confirmation email will get sent every time the item is modified.
B. Create a hidden column to check if email has already been sent or not. For workflows that start when items are modified, it’s advisable to create a hidden column on the list/library to record whether an email is sent or not.
Create hidden column for email confirmations
1. Go to the list or library that the workflow is on. Click on the List/Library tab and select the List/Library settings icon. Once on the List Settings page, click Create column link under the Columns section:
2. Column Name: enter a descriptive title for the type of email, Type of column: choose the Choice option, Required: No, Type Choices: No Yes, Using: dropdown, Default Value: No, uncheck the add to default view option:
**After you have your new column all setup, click on the OK button to create the column and return to the list/library settings page.
3. Next click on the Advanced settings link on the list/library settings page:
4. Select Yes for ‘Allow management of content types’. Click on the OK button to return list/library settings page.
5. On the list/library settings page click on the content type that is displayed in the Content Type section. Depending on the type of list or library, this could be ‘Task’, ‘Item’ or ‘Document’.
6. The new column you just created should be displayed along with an ‘Optional’ Status. Click on your new column.
7. Select Hidden from the column settings options.
**Your new column is now on the list and will be hidden from when people are creating, editing or viewing items. You can now return to your list or library.
8. Once you have the hidden column on your list/library, the next step is to create a Nintex Workflow on the list or library. Add a Run If action to your workflow, and put a Send Notification action right below the Run If action:
9. Configure your Run If action so it runs if your Email Confirmation field equals No. Optionally you can add a second condition it it’s needed for you process. In the example below, I added a second condition that only runs if the % complete equals 100.
10. Add a ‘Set field value’ action under the send notification action, still inside the Run if action. Configure the set field value to set your Email Confirmation field to Yes. This way once the email is sent, the confirmation field is set to Yes, and the Run If condition will no longer send that email.
11. Your finished workflow should look something like this, a Run If action with both a Send Notification action and a Set Field Value action inside the Run If action: